Search

Pancreatic ductal adenocarcinoma (PDAC) is resistant to current treatments but lectin-based therapy targeting cell surface glycans could be a promising new horizon. Here, we report a novel lectin-based phototherapy (Lec-PT) that combines the PDAC targeting ability of rBC2LCN lectin to a photoabsorber, IRDye700DX (rBC2-IR700), resulting in a novel and highly specific near-infrared, light-activated, anti-PDAC therapy. Lec-PT cytotoxicity was first verified in vitro with a human PDAC cell line, Capan-1, indicating that rBC2-IR700 is only cytotoxic upon cellular binding and exposure to near-infrared light. The therapeutic efficacy of Lec-PT was subsequently verified in vivo using cell lines and patient-derived, subcutaneous xenografting into nude mice. Significant accumulation of rBC2-IR700 occurs as early as 2 hours postintravenous administration while cytotoxicity is only achieved upon exposure to near-infrared light. Repeated treatments further slowed tumor growth. Lec-PT was also assessed for off-target toxicity in the orthotopic xenograft model. Shielding of intraperitoneal organs from near-infrared light minimized off-target toxicity. Using readily available components, Lec-PT specifically targeted pancreatic cancer with high reproducibility and on-target, inducible toxicity. Rapid clinical development of this method is promising as a new modality for treatment of pancreatic cancer.

Introduction: We have previously demonstrated that fucosylated glycans (H type-3 motifs) are expressed in pancreatic cancers and a recombinant lectin, called rBC2LCN, binds to these glycans specifically (Shimomura O, Oda T, et al: Mol Cancer Ther 2018). This rBC2LCN lectin has development potential for payload delivery to pancreatic cancer cell surfaces. However, the lectin has cross reactivity to noncancerous cells, including renal tubular epithelial cells. Therefore, for the purpose of targeting cancer cells more specifically, we have applied this lectin-based carrier system for near-infrared photoimmunotherapy (NIR-PIT). This lectin-based PIT (Lec-PIT), using a lectin-photoabsorber conjugate (BC2-IR700), successfully showed anti-tumor effect upon NIR-light exposure in in vivo mouse model (Kuroda et al: AACR Annual Meeting 2022). In this study, we assessed biodistribution of BC2-IR700 and investigated that Lec-PIT minimized off-target toxicity by shielding of intraperitoneal organs from near-infrared light in orthotopic model of pancreatic cancer. Material and Methods: BC2-IR700 was synthesized by conjugating rBC2LCN lectin with IR700 NHS ester. Capan-1, an H type-3-positive human pancreatic cancer cell line, was used as a model which is bound by rBC2LCN lectin. Capan-1 was transfected with a GFP-luciferase-encoding lentivirus, which was abbreviated as Capan-1-GFP-luc. We used Capan-1-GFP-luc cells for engraftment into nude mice to visualize orthotopic pancreatic tumors by luciferase bioluminescence. Lec-PIT was performed by exposing to NIR light (100 J/cm2) at 6 h following BC2-IR700 intravenous administration (20 μg/mouse). Results: Ex vivo examination was performed to assess the biodistribution of BC2-IR700 at 6 hours after administration. Each organ and tumor were resected from a pancreatic cancer xenograft mouse and imaged using IVIS Spectrum. A high fluorescence intensity was observed in tumor, kidney and liver. For Lec-PIT in an orthotopic model of pancreatic cancer, NIR light was directed at the tumor intraperitoneally under laparotomy with the rest of the organs shielded by aluminum foil. Lec-PIT group showed significantly lower bioluminescence during the experimental period (P < 0.01 vs control group). No hematological parameters, including CRE, AST and ALT, differed significantly between the control and Lec-PIT groups. Additionally, histological examination of intraperitoneal organs collected from the Lec-PIT group showed no abnormal findings. Conclusions: We described that Lec-PIT is safe and any unintended damage due to accumulation of BC2-IR700 can be mitigated by shielding these areas with NIR-reflective material. This novel PIT targeting cell surface glycans could be a promising therapeutic strategy for the treatment of pancreatic cancer. Citation Format: Yukihito Kuroda, Osamu Shimomura, Hiromitsu Nakahashi, Yoshihiro Miyazaki, Takahito Nakajima, Hiroaki Tateno, Tatsuya Oda. Lectin-based photoimmunotherapy targeting cell surface glycans for pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr B083.

Introduction: Since protein targets in cancer therapy largely have been explored, glycans would be attractive alternative targets. We had previously discovered a fucosylated glycan epitope highly expressed on pancreatic cancer cells, and a lectin probe called rBC2LCN, which can be used as a specific targeting bullet to this glycan (Shimomura O, Oda T, et al: Mol Cancer Ther 2018). We now then hypothesized that, this lectin-based cancer-targeting strategies should be reasonably applicable to near-infrared photoimmunotherapy (NIR-PIT). NIR-PIT have already developed using a conjugate of a photoabsorber, IRdye700DX (IR700), and a monoclonal antibody which recognizes protein antigens on the target cells. In this study, we firstly developed a lectin-photoabsorber conjugate (BC2-IR700) and investigated a new cancer therapy targeting cancer cell surface glycans. Material and Methods: We developed BC2-IR700 by conjugation of rBC2LCN lectin with IR700 NHS ester. A pancreatic cancer cell line Capan-1 was used as a model which is bound by rBC2LCN. The cytotoxic effect of NIR-PIT with BC2-IR700 was first evaluated in vitro. We then evaluated the anti-cancer effect of BC2-IR700 in vivo using pancreatic cancer xenograft mice including subcutaneous tumor model. Results: The product of BC2-IR700 was confirmed by SDS-PAGE, that showed reasonable 16KDa sharp band with clear fluorescence intensity. After incubation with BC2-IR700, Capan-1 cells showed high fluorescence signal, which was confirmed with flow cytometry and fluorescence microscopy. BC2-IR700 was detected on the cell surface of Capan-1 after incubation for 1h. Immediately after exposure to NIR light, the cell death of Capan-1 was induced and the cytotoxicity significantly increased in a light-dose-dependent manner. After intravenous administration of BC2-IR700 into pancreatic cancer xenograft mice, BC2-IR700 was observed in vivo fluorescence imaging to be accumulated in tumor. NIR-PIT was performed by exposing to NIR light (100 J/cm2) at 6 h following BC2-IR700 intravenous administration (20 μg/mice). Tumor growth was significantly inhibited in the NIR-PIT treatment group compared with the other control groups such as no treatment, BC2-IR700 only, and NIR light exposure only (P < 0.05). Conclusions: The lectin-photoabsorber conjugate, BC2-IR700, was able to be sufficiently applied for NIR-PIT in in vivo mouse model. The novel NIR-PIT targeting cell surface glycans could be a promising therapeutic strategy for the treatment of pancreatic cancer. Citation Format: Yukihito Kuroda, Osamu Shimomura, Hiromitsu Nakahashi, Tomoaki Furuta, Yoshihiro Miyazaki, Takahito Nakajima, Hiroaki Tateno, Tatsuya Oda. Near-infrared photoimmunotherapy for pancreatic cancer: Targeting cell surface glycans using lectin-photoabsorber conjugate (LPC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5328.